Fundamentals, water, acids, bases and buffers

Question 1

Enzyme deficiency in alkaptonuria

Answer 1

Homogentisate oxidase

Question 2

Enzyme deficiency in homocystinuria

Answer 2

Cystathionine synthase

Question 3

Enzyme deficiency in MSUD

Answer 3

Branched-chain alpha-ketoacid dehydrogenase

Question 4

Enzyme deficiency in PKU

Answer 4

Phenylalanine hydroxylase

Question 5

Hydroxylation

Answer 5

Introduces an -OH group

Question 6

Decarboxylation

Answer 6

removes a carboxyl group and release CO2

Question 7

IN oxidation reactions electrons are ____

IN reduction reactions electrons are ____

Answer 7

Lost

Gained

Question 8

___% of our body wieght is water

Answer 8

50%

Question 9

Unique properties of water

Answer 9

Great nucleophile
Great buffer
Hydrogen bonds
Great solvent

Question 10

pH =

Answer 10

• log [H+]

Question 11

Hormones that monitor blood volume and osmolality

Answer 11

ADH and aldosterone

Question 12

Buffers consist of:

Answer 12

Undissosciated acid and its conjugate base

Question 13

A buffer has its greatest buffering cpacity at:

Answer 13

or near its pKa (+/- 1)

Question 14

pKa =

Answer 14

• log Ka

Question 15

Two factors that determine the effectiveness of a buffer

Answer 15

its pKa relative to the pH of a solution

and

its concentration

Question 16

Norma pH range for blood

Answer 16

7.35 - 7.45

Question 17

Blood pH is maintained by:

Answer 17

H2CO3/HCO3- buffer system

Question 18

Ka is:

Answer 18

acid dissociation constant, larger Ka, stronger acid

Question 19

pKa is:

Answer 19

• log Ka

smaller pKa, stronger acid

Question 20

Henderson-Hasselbalch equation:

Answer 20

pH = pKa + log [A-]/[HA]

Question 21

Normal metabolism generates:

Answer 21

CO2, lactic acids and ketones, and inorganic acids

Question 22

How does the body void of acid?

Answer 22

Expiration of CO2

Excretion of ammonium (NH4+)

Question 23

Respiratory acidosis caused by:

Answer 23

Hypoventilation > leads to an increase in CO2 > increase H+ > decreased pH

Question 24

Metabolic acidosis caused by:

Answer 24

Addition of a strong acid and loss of HCO3- (via diarrhea and/or abnormal kidney function)

Question 25

Buffer system equation (dont forget enzyme):

Answer 25

CO2 + H2O H2CO3 HCO3- + H+

Via carbonic anhydrase

Question 26

Respiratory alkalosis is caused by:

Answer 26

Hyperventillation > leads to decrease in CO2 > leads to loss of H+ > increased pH

Question 27

Metabolic alkalosis caused by:

Answer 27

Addition of a strong base and loss of acid (via vomiting)

Question 28

Gibbs free energy:

Answer 28

∆G = ∆H -T∆S

Question 29

-∆H vs +∆H

Answer 29

-∆H is favorable and leads to a lower energy state, heat flow out of the system

+∆H is unfavorable and leads to higher energy state, heat flow into a system

Question 30

-∆S vs +∆S

Answer 30

-∆S more favorable as ti leads to increase in entropy

+∆S less favorable as it leads to a decrease in entropy

Question 31

What is Keq

Answer 31

Equilibrium cosntant

Temperature dependent

Question 32

Keq =

Answer 32

[X]^x[Y]^y / [A]^a[B]^b

for reaction:

aA +bB xX + yY

Question 33

Standard state conditions

Answer 33

298K, 1M, 1 atm, pH 7

Question 34

∆G°
vs
∆G°’

Answer 34

Gibbs free energy under standard conditions

Same, but used for biochemistry purposes

Question 35

∆G° > 0 (+)

Answer 35

Endergonic
non spontaneous
favors reactants

Question 36

∆G° < 0 (-)

Answer 36

Exergonic
spontaneous
favors products

Question 37

Le Chatliers Principle

Answer 37

Systems at equilibrium will respond to applied stress with a shift that counteracts applied stress

Question 38

+∆H
vs
-∆H

Answer 38

Endothermimc

Exothermic

Question 39

Chemical reaction that is crucial to creating energy currency ATP

Answer 39

Phosphoryl group transfer

Question 40

Favorability of ATP -> ADP + Pi

Answer 40

Very favorable
∆G &laquo_space;0
ATP hydrolysis is useful in coupling reactions

Question 41

Cystine

Answer 41

When 2 Cysteine’s come together by a disulfide bond

Question 42

Charge on α-amino group

Answer 42

pronated (+) at a pH 7

Question 43

Charge on α-carboxyl group

Answer 43

dissociated (-) at pH 7

Question 44

Charge on basic AA’s

Answer 44

Arginine, lysine, histidine are positive at pH 7

Question 45

Charge on acidic AA’s

Answer 45

Aspartic acid and glutamic acid are negative at pH 7

Question 46

Isoelectric point

Answer 46

Point at which overall charge on AA is 0

Question 47

If the pH is below pKa:

Answer 47

It will be pronated

Question 48

If the pH is above pKa:

Answer 48

It will be deprotonated

Question 49

pK1

Answer 49

α-carboxyl group (pKa ~2)

Question 50

pK2

Answer 50

α-amino group (pKa ~9)

Question 51

First line of defense against pH shift

Answer 51

Bicarbonate buffer
Phosphate buffer
Protein buffer (ie hemoglobin)

Question 52

Second line if defense against pH shift

Answer 52

Respiratory mechanism (excretion of CO2)
Renal mechanism (excretion of H+)

Question 53

Why does a patient with severe anemia have a decreased capacity to use the bicarbonate buffer system?

Answer 53

Decreased amount of carbonic anhydrase in red blood cells

Question 54

Enzyme deficiency in homocystinuria:

Answer 54

Cystathione synthase

Question 55

Enzyme deficiency in alkaptonuria:

Answer 55

Homogentisate oxidase

Question 56

A class of chemical reactions that are of great importance in the formation of energy currency ATP

Answer 56

Phosphoryl group transfer